Booster brake



May I3, l1930. BLAcKMoRE 1,758,139

BOOSTER BRAKE Filed Mardh 8, 1925 sa "wz 4a az l Patente 13, 193C LLOYD BICKMORE, 0F HIGHLAND PARK, yMICHIG'JI',l ASSIGNOR, BY MESNE ASSIGN MENTS, TO BENDIX BRAKE COMPANY, F CHICAGO, ILLDVOIS, A CORPORATION OF ILLINOIS Application led'arch 8, 1928. Serial No. 623,718.

K of the road wheels of an automobile.

An object of the invention is to simplify the connections of brakes of this type by arranging the primary brake and the booster brake in such a manner that they operate on the same drum so that they may be directly connected with one another. In' one form which I have found satisfactory, the primary brake is in the form of an expansible and cont-ractable friction band associated with the drum and arranged to be operated by angular movementof a booster shoe which is radially movable into frictional engagement with the same drum under the control of the driver. In a particular embodiment illustrated in the accompanying drawings this band includes a. pair of pivota-lly mounted shoes arranged to be forced apart by a cam which is geared to an angularly movable support on which the booster shoe is slidably mounted. p

Other objects and features of the invention, including various novel combinations and desirable particular constructions of the different parts, will beapparent from the following description of the illustrative embodiment of the invention shown in the accompanying drawings, in which:

Figure l is a vertical section on the line 1"1 of Figure 2 showing the parts of the brake in side elevation and showing the drum in section;

Figure 2 is a section on the line 2-2 of Figure 1, showing the arrangement of the various parts with respect to a semifloating drive axle;

Figure 3 is a view corresponding to the upper part of Figure l and showing the operation of the booster shoe when the drum is turning in a counterclockwise direction; and

Figure 4 is a similar view of the operation of the booster shoe when the drum is moving in a clockwise direction.

. In the particular, form shown in the drawings, the brakeincldes a drum 10 'of any suitable construction, which is secured to the road wheel 12 of an automobile. This wheel is shown as being arranged to be driven by a.

drive axle 14 having a stationary casing 16 which supports various parts of the brake.

In the form of the invention which is atv present preferred, the prima-ry brake cooperating with drum 10 comprising an expansible and contractable friction band shown as including a pair of shoes 18 and 20 pivotally mounted at 22 and 24 on a stationary plate 2C carried by the axle casing 16. .These shoes are arranged to be operated by being forced apart by angular movement of a cam 28 carried by a short shaft 30 mounted in plate 26, to which shaft there is keyed a gear sector 32 meshing with a gear sector carried by or integral with a support 34 mounted for angular movement onthe axle casing 16 about the axis of drum 10. Slidably mounted. in

grooves in the forked outer end of support 34 is a booster shoe 36 which is yieldingly urged toward the axis of drum 10 by a pair of coil springs 38 and which is radially movable into frictional engagement with drum 10. 'I he booster shoe is pivoted to an operating llnk 40 connected to one arm of a bell crank lever 42, pivoted at 44'on the stationary plate 26. The bell crank lever 42 is operated by the brake pedal or any other suitable controlllng device connected thereto by means of a link 46.

In the operation of the above described mechanism, and assuming that the brake is mounted on the road wheel of an automobile which is in motion, operation of the brake pedal or other controlling member rocks bell crank lever 42 to move the booster shoe 36 into frictional engagement with the interior surface of the brake drum 10. If thebrake drum is rotating in a counterclockwise direction this will result in angular movement in a counterclockwise direction of support`34 as shown in Figure 3. If the drum is turning in a clockwise direction the support 34 will also vbe moved in a clockwise direction as l shown in Figure 4. In either case cam 28 is turned, by reason of being geared to support 34, to force the shoes 18 and 20 apart into Africtional engagementwitli drum 10.- When move the booster shoe 36 out of engagement with drum l0.\whereupon a return spring 48 pulls the shoes 18 and 20 toward one another ication and in the appended claims, is 1nrespect to the drum, mounted on the support for movement theretended toV be understood as a convenient designation for any sort of member which is to be braked, i. e., this term is intended to be construed broadly as covering any member of which the movement is to be retarded, except where. specifically described otherwise. The full scope of the invention which is claimed and which it is desired to protect by U. S. Letters Patent is defined by the following claims.

I claim:

1. A brake comprising, in combination, a drum, retardng means cooperating therewith, a support angularly movable about the axis of the drum, a booster member carried by the su port and movable thereover radially into fractional engagement with the drum, and means operated by angular movement of the support for operating said retarding means, the retarding means and said member engaging the same zone of the drum.-

A2. A brake comprising,in combination, a drum, including a. pairof brake shoes Within the drum, a support angularly movable with a booster shoe slidably over into frictional engagement with the inside of the drum, and means operated by the angular movement of the support for separatin said shoes and forcing them into frictiona engagement with the drum.

3. A brake comprising, in combination, a drum, a pair of brake shoes each anchored at one end within the drum, an angularly movy able support, a booster shoe slidably mountedlon said support for movement into frictional engagement with the drum between the4 anchored ends of the shoes, and connections operated by angular movement of the support for operating said shoes.

4. A brake comprising, in combination, Va drum, an expansiblel and contractableifriction device associated therewith, an angularly movable support, a booster member mountl ed1on the support for movement into frictional engagement with the drum, and a friction device operating member geared to the. support to be operated by angular movement thereof, the -booster member and said friction device engaging the same zone of the drum. 5. A brake comprising, in combination, a drum, friction means within the drum inauxiliary shoe tively with the support and the cam in such a manner that the shoes are forced apart by angular movement of the support in eitherl direction, a booster shoe slidably mounted on the support and yieldingly urged toward the y the drum, and driver-controlled conaxis o nections for moving the booster shoe radially into frictional engagement with the drum to operate as described. A

6. A brake comprising, in combination, a drum having an annular flange, a booster shoe mounted for radial movement against the inside of the flange and for limited angular movement with the drum, a pair of shoes each pivoted within the drum at the end adjacent to the booster shoe. a brake cam between the unanchored ends of the pair of shoes and diametrically opposite the booster shoe and connections from the booster shoe for operating/the cam.

7 A brake comprising, in combination, a drum having an annular flange, a booster shoe of segmental shape mounted for driver-controlled radial movement against the inside of the flange and for limited angular movement 'with the drum, a pair of segmental shoes substantially. longer than the booster shoe pivoted at opposite sides of the booster shoe the pivoted ends'being spaced apart an angular distance greater than the maximum angular movement of the booster shoe, a brake cam between the other ends of the pair of shoes diametrically opposite the idle position of the booster shoe, and connections from the booster shoe moves angularly.

8. A brake comprising, in combination, a drum, a pair of shoes each anchored at one end within the drum, an angularly-movable ositioned between the anchored ends of t e pair of shoes, means for forcing the auxiliaryshoes against the drum, and connections operated by the angular movement of the auxiliary shoe to force atv least one of the anchored against the drum.

-9. A brake comprising, in combination, a drum, two brake shoes acting thereon, one shoe being angularly movable with the drum, and the other shoe being anchored therein at the end adjacent to the first shoe a cam engaging the unanchored end of the second shoe to force it outwardly against the drum, and a connection operated by angular movement of the first shoe to rock said cam.

10. A brake comprising, in combination, a drum, a pair of anchored shoes-within the drum, an auxiliary shoe positioned between shoes outwardly the anchored ends of the pair of shoes and angularly movable with the drum, andmeans operated by angular movement of the auxiliary shoe with the drum in either direction to force the remote end of at least one ofv the anchoredshoes against the drum.

11.` A brake comprising. in combination, a drum, a pair of anchored shoes within the, drum, a support pivoted Within the drum and extending diametrically thereacross` an aux-iloperating mechanism for said servo shoe,

iary shoe mounted upon one en d of the support and'movable with respect thereto into engagement with the drum and angularly movable therewith and with the drum, and means operated by angular movement of the auxiliary shoe with the drum in either-direction to force the anchored shoes apart against thedrum.

12. A brake having main and servo shoes arranged end to end, said main shoe being anchored at the end adjacent to the servo shoe, a pivoted cam engaging the main shoe, and means operated by the servo shoe for turnin the cam;

13. rake mechanism comprising, incombination, a drum, a brake shoe anchored at one end within the drum, a diametrical support pivotally mounted AWithin thedrum. a servo shoe mounted upon one end of the support-adjacent to theanchored end of the :first shoe and means coupling the opposite end of the support to the unanchored end of the irs't shoe to actuate such shoe.

14. Brake mechanism comprising, in combination, a drum, a brake shoe anchored at one end within the drum, a support pivoted within the drum, a servo shoe slidably mounted upon one end of the support to travel thereover into engagement with the drum,

means actuated by the pivotal movement of ,the support for urging the. anchored shoe into the drum. i

15. Brake mechanism comprising, in combination, a drum, a brake shoe arranged within the drum to be urged thereagainst, a support mounted within the drum for angulart` movement, a servo shoe mounted upon one 'end of the support for outward movement vwith respect thereto into engagement with the drum, spring means tensioning said sho inwardly with respect to the support, an means connecting the support with that end of the brake shoe urtherst removed from theservo shoe to urge said brake shoe toward the drum upon determined angular movement of the support. 16. Brake mechanism comprising, incombination, a drum, a retarding member operable to lengage the drum, an angularly shiftable support, a servo shoe mounted thereon for slidable movement thereover into` engagement with thedrum, and means operable by the support in its angular movement engaging the retarding member at a point substantially diametrically opposite the servo shoe to apply the retarding member to the drum.

port within the drum, a servo shoe mounted v upon one end of the support for slidable travel outwardly thereover into engagement withthe drum between the anchored ends of the pair of shoes, and mechanism actuated by the opposite end of the support in its angular movement to spread the anchored shoes outwardly against the drum.

18. A brake comprising, in combination, a drum,a pair of shoes eaeh anchored at one end ,within the drum, a servo shoe positioned between the anchored ends of the -pair of shoes, and means operable by the servo shoe for exerting a force of application upon the pair of shoes.

19. A brake comprising, in combination, a drum, a pair of shoes each anchored at one end within the drum,'a servo shoe positioned between the anchored ends of .the pair of shoes, means operable to force the servo shoe into engagement with the drum and means operable by the servo shoe to force the unanchored ends of the pair of shoes against the drum. t

20. A brake comprising, in combination, a drum, a pair of retarding members each anchored at one end adapted to be brought ends of the retarding members and adapted to be brought into engagement With the drum, y

and angularly shiftable therewith and means operable by the auxiliary member for exerting a force on the pair of members tending to force them into engagement with the drum. 21. A brake comprising, in combination, a drum, retarding means provided with a pair of spaced apart anchors, a servo device positioned between the anchors of the retarding means, and means operable by the-servo deviceto exert a force upon the retarding means tending to apply it tothe drum. 22. A brake comprising a drum and at least three shoes arranged with their friction faces end to. end fwithin the drum, in combination with an applying device engaging the adjacent ends of two vof the shoes substantially within the circumferential path of the three shoes, said two shoes being anchored at their other ends. i

23. A brake comprising a drum and at least three shoes arranged with their friction faces 1-5 end to end within the drum, 1n combination roo with an applying device engaging the adjacent ends of two of the shocsat a point substantially diametrically opposite the third shoe, said two shoes being anchored at .their other ends, at leastone of the shoes being arranged to force at least one of the others against the drum. Y.

24. A brake comprising a drum and/'two shoes having an applying device acting on their ends at one side of the drum andhaving their other ends anchored, in combination with a third shoe arranged between the anchored ends of said two shoes and means for urging the third shoe against the drum.

25. A brake comprising a drum and at least three shoes arranged with their friction faces end to end within the drum, in combination with applying means including a part positioned between the adjacent ends of two of the shoes and substantially diametrically opposite the third shoe, said two shoes being anclored at their ends adjacent to the third s oe. Y

26. A brake comprising a druln and at least three shoes arranged with their friction faces end to end within the drum, in combination with applying means coupling one shoe with another whereby angular movement of the one serves to urge the other against the drum including a part positioned between the adjacent ends of the shoes and substantially diametrically opposite the third shoe, said two shoes being anchored at their ends furtherst removed from said part.

27. A brake comprising, in combination, a drum, a pair of shoes each anchored at one end within the drum, a servo shoe ositioned between the anchored ends of the pa1r of shoes and power multiplying means operable by the servo shoe exerting a force of application upon the pair of shoes.

28. A brake comprising, in combination, a drum, retarding means arranged within the drum having a pair of spaced apart ends and anchors cooperating with said ends, a servo device arranged between said anchors and provided with powervnultiplying means operable thereby to exert a vforce upon said retarding means tending to urge it against the drum. Y

A29, A brake comprising, in combination, a

drum, retarding means operable to engage the drum, a support pivoted within the drum for angular movement, said support provided with spaced apart guide members, a servo shoe slidably mounted between said guide members for movement toward andA away from the drum, means operable to urge the servo shoe against the drum and means including said support operable by the servo shoe to urge said retarding means against the In testimony whereof I aix my signature.

LLOYD BLACKMORE. 

